_Portulaca_ (Portulaca): flower, epigynous or semi-epigynous; fruit, a
pyxidium. The stamens vary in number, and are most frequently placed in
groups (in consequence of splitting) opposite the petals.--_Montia_:
the corolla is slightly gamopetalous, but cleft on the posterior side
(Fig. 367), and as a consequence of the larger size of the lateral
petals, slightly zygomorphic; 3 stamens.--_Calandrinia_; _Talinum_;
_Anacampseros_; _Claytonia_.
125 species; mostly in warm and temperate countries, especially
the arid parts of S. Am. and the Cape. _Montia fontana_ (Blinks)
is a native plant. _Portulaca oleracea_ is cultivated as a
pot-herb in the south of Europe. A few species of _Portulaca_
and _Calandrinia_ are ornamental plants.
Order 7. =Nyctaginiaceæ.= The characteristic feature of this order
is the _single_, regular, _united_, and often petaloid perianth, the
lower part of which generally persists after flowering and embraces
the fruit as a false pericarp. The upper portion is most frequently
_valvate and folded_, or simply valvate in æstivation. The number of
stamens varies. The free gynœceum is _unicarpellate_ and has 1 ovule.
The fruit is a _nut_, but becomes a _false drupe_, since the lower
persistent portion of the perianth becomes fleshy (as in _Neea_, where
this fleshy part is almost always crowned by the upper persistent
part of the perianth. In the majority of the Mirabileæ the lower part
becomes the dry _anthocarp_, while the upper petaloid part falls away
after flowering). Finally, a peculiar involucre is formed around the
flowers by free or united floral-leaves.--The majority are herbs, some
are trees (_Pisonia_, etc.); _Bougainvillea_ is a liane. The stems
are often nodose and swollen at the nodes; the leaves are simple,
penninerved, scattered, or opposite, without stipules. ~In some, the
vascular bundles are scattered; stem anomalous.~
_Mirabilis_; the structure of the stem is abnormal. Dichasial branching
with continuation from the second bracteole, thus forming unipared
scorpioid cymes. The perianth is petaloid, funnel-shaped, and has
a folded and twisted æstivation resembling that of the corolla of
the _Convolvulaceæ_; the upper coloured portion falls off after
the flowering. Outside, and alternating with it, is a 5-partite,
sepaloid involucre of 5 spirally-placed floral-leaves.--_Oxybaphus_;
the involucre envelops 1–3 dichasial flowers.--_Bougainvillea_; the
involucre is rose-coloured, 3-leaved, and envelops 3 flowers (placed
laterally; the terminal flower wanting). The leaves of the involucre
in _Boerhaavia_, _Pisonia_, _Neea_, and others are reduced to teeth or
scales.
157 species; mostly in tropical countries, and especially S. Am.
Species of _Mirabilis_ (Am.) are ornamental plants. Theïn is
found in _Neea theïfera_ Oersted (discovered by Lund in Lagoa
Santa, Brazil), which may be used as a tea-plant.
Order 8. =Aizoaceæ.= Only 3 _whorls_ are found in the flower,
which _alternate_ with one another when their leaves are equal
in number. The first is sepaloid, the third one the carpels,
and the intervening one is either uncleft, in which case it is
developed as stamens, or it is divided into a large number of
members which then all become stamens (arranged in groups), or
the outermost ones become developed as petals. The fruit is most
frequently a capsule with several loculi. Most of the species
are herbs with thick, fleshy stems, and exstipulate leaves. The
structure of the stem is usually anomalous.
=1.= AIZOIDEÆ have hypogynous or perigynous flowers with (4–)
5 perianth-leaves; stamens single, or (by splitting) in groups
of 2–3, alternating with the perianth-leaves. The gynœceum
(with 3–5 carpels) has 3–5 loculi in the ovary, and most
frequently numerous ovules in each loculus, borne on the central
placenta formed by the edges of the carpels. The fruit is a
capsule. The inflorescences are dichasia and unipared scorpioid
cymes.--_Aizoon_, _Mollugo_, _Sesuvium_, and others are herbs or
bushes, most frequently hairy.
=2.= MESEMBRIANTHEMEÆ have semi- or wholly-epigynous
flowers.--_Tetragonia._ The perianth is 4 (more rarely
3–5–6)-merous. Stamens single, or (by splitting) in groups
alternating with the perianth-leaves. There is an indefinite
number of carpels, and each loculus of the ovary contains
_only_ 1 pendulous ovule. Fruit a nut or drupe. The flowers
arise singly in the leaf-axils, with an accessory foliage-bud
below them; in some instances there is also an accessory
flower between this bud and the flower. Southern hemisphere,
especially at the Cape; _T. expansa_, New Zealand Spinach, is a
fleshy plant which is cultivated as a pot-herb (Japan, Austr.,
S. Am.).--_Mesembrianthemum_: the flowers are 5-merous; the
numerous linear petals and the still more numerous stamens all
arise by the splitting of 5 or 4 protuberances (primordia)
alternating with the sepals. The ovary presents another
characteristic peculiarity: the carpels alternating with the
5–4 stamens form an ovary (with several loculi) with the ovules
at first borne, as in other cases, on the _inner_ corner of the
inwardly-turned carpels; but during the subsequent development
the whole ovary is so turned round that the placentæ become
parietal and the ovules assume, apparently, a position very
rarely met with in the vegetable kingdom: on the dorsal suture
of the carpels. Shrubs or under-shrubs, more rarely herbs
with fleshy stems and simple, entire, more frequently thick
or triangular leaves, containing a quantity of water. The
flowers open about noon, and are brightly coloured, generally
red or red-violet, but odourless. The capsules dehisce in
rainy weather. 300 species, mostly found at the Cape. Some are
ornamental plants. _M. crystallinum_ (the Ice-plant) and others
are covered with peculiar, bladder-like, sparkling hairs, the
cell-sap of which contains salt--these serve as reservoirs of
water.